Signal stabilization in a dielectric sensor assembly

ABSTRACT

A non-resistive contact sensor assembly includes an electric field sensor device, including a dielectric component for receiving an electrical signal from an object of interest and a signal processing component for processing the electrical signal, a voltage regulator for controlling voltage to the dielectric component and the signal processing component, and a common ground reference for the dielectric component and the signal processing component.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is U.S. continuation patent application of, andclaims priority under 35 U.S.C. §120 to, U.S. nonprovisional patentapplication Ser. No. 13/835,762, filed Mar. 15, 2013, which patentapplication is incorporated by reference herein, and which applicationis itself a U.S. non-provisional patent application of, and claimspriority under 35 U.S.C. §119(e) to, U.S. provisional patent applicationSer. No. 61/759,827 to Dawson, filed Feb. 1, 2013 and entitled “SIGNALSTABILIZATION IN A DIELECTRIC SENSOR ASSEMBLY,” which '827 applicationis incorporated by reference herein in its entirety. Additionally, theentirety of each of the following co-pending, commonly-assigned U.S.patent applications, and any application publication thereof, isexpressly incorporated herein by reference:

-   -   (a) U.S. provisional patent application Ser. No. 61/671,647 to        Dawson, filed Jul. 13, 2012 and entitled “REDUCING MOVEMENT AND        ELECTROSTATIC INTERFERENCE IN A NON-RESISTIVE CONTACT SENSOR        ASSEMBLY;”    -   (b) U.S. provisional patent application Ser. No. 61/695,986 to        Dawson, filed Aug. 31, 2012 and entitled “SIGNAL STABILIZATION        IN A NON-RESISTIVE CONTACT SENSOR ASSEMBLY;”    -   (c) U.S. non-provisional patent application Ser. No. 13/834,664,        filed Mar. 15, 2013, and entitled, “REDUCING MOVEMENT AND        ELECTROSTATIC INTERFERENCE IN A NON-RESISTIVE CONTACT SENSOR        ASSEMBLY;” and    -   (d) U.S. non-provisional patent application Ser. No. 13/834,918,        filed Mar. 15, 2013, and entitled, “SIGNAL STABILIZATION IN A        NON-RESISTIVE CONTACT SENSOR ASSEMBLY.”

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under contract numberW911NF-12-C-0004 awarded by DARPA. The government has certain rights inthe invention.

COPYRIGHT STATEMENT

All of the material in this patent document is subject to copyrightprotection under the copyright laws of the United States and othercountries. The copyright owner has no objection to the facsimilereproduction by anyone of the patent document or the patent disclosure,as it appears in official governmental records but, otherwise, all othercopyright rights whatsoever are reserved.

BACKGROUND OF THE PRESENT INVENTION

1. Field of the Present Invention

The present invention relates generally to electric field sensors, and,in particular, to signal stabilization in a non-contact resistivecontact sensor assembly.

2. Background

Conventional electrodes act as a current transducer converting ioniccurrents into electronic ones so electrophysiological status can beassessed. The uses for this are many and broadly range from assessmentof neural (EEG), and cardiac (ECG) and skeletal (EMG) muscle activity.

This approach requires conductive contact with the source and hasinherent problems. The first of these is the requirement of clean skinexposure. This requirement may compromise continuous usability due tothe effects of environmental contaminants, both on the skin and in theatmosphere; extremes of temperature and their resulting general effecton skin due to physiological reactions such as “goose bumps” andexcessive sweating as well as other phenomena; and potential reactionsto conductive materials. The process of preparing skin and securing agood conductive contact can also decrease compliance, especially in ifintended for continuous day to day use. Furthermore, during exercise,the physicality can result in electrodes being displaced. Other issuesinclude shorting between electrodes, especially when placed in closeproximity to each other, and charge transfer which has potential safetyimplications as well as the issue of the measurement process corruptingthe signal.

The problems, outlined above, may be at least partially solved by theuse of capacitive electrodes (non-resistive contact sensors) as theyacquire signals through capacitive coupling, not requiring resistivecontact with the source. They provide many benefits, including the factthat no electrical contact is required, and so no skin preparation orconducting pads are necessary and they can be readily moved or relocatedto get an optimal signal. In addition, they can be miniaturized, theyhave very low power requirements, and they can be embodied as passiveelectric field sensors with the result that adjacent sensors do notinterfere with each other.

The use of capacitive electrodes for electrophysiological monitoring isnot a recent innovation, with Richardson describing it for acquisitionof the cardiac signal in 1967 (see The insulated electrode: a pastelesselectrocardiographic technique. Richardson P C. Proc. Annu. Conf. onEngineering in Medicine and Biology 7: 9-15(1967)). This system was,however, flawed being prone to problems including poor signal to noiseratio, voltage drift, electrostatic discharge and parasitic capacitance.These are still problems with capacitive sensor technologies today. Manyof those problems have been addressed, at least partially, but problemswith signal stability interference still plague this technology. Signalstability interference is especially problematic during movement.Movement may lead to a variety of issues that may compromise continuoussignal acquisition including contact electrification between the bodysurface and the sensor electrode; charge build-up on the body resultingin baseline shift and potential saturation if occurs too rapidly; andmovement of the sensor relative to the body that can also lead tobaseline shift and saturation (railing).

When dry contact electrodes are placed in direct contact with a person,and particularly when they are moved, triboelectric effects (electricalcharges created by sliding friction and pressure) are frequentlygenerated. Triboelectric effects of this nature may cause contactelectrification where static charges may be delivered to the pick-upelectrode. This static charge can produce a near-direct current (DC) orvery low frequency drift in the sensor that may interfere with thephysiological alternating current (AC) signal that is being measured ormay saturate the sensor causing railing, after which the sensor takestime to return to being able to produce a usefulphysiologically-relevant output. If the electrode moves relative to thebody, it will also pick up a geoelectric displacement signal. That is,the effect of the body, an electrically active structure, moving throughthe geoelectric field, which is on the order of 100 Vm⁻¹, will causerelative polarization of the sensor that will displace the baseline andmay cause the sensor to saturate. An additional source of interferenceis that of clothing moving on the body. As clothing moves on the body,charge separation can occur when materials that are separated on thetriboelectric series donate or receive electrons from each other. Aftera material becomes charged it may discharge onto the surface where anelectric potential is being measured, thereby interfering with signalacquisition.

Various issues can arise as a result of these various forms ofinterference. For example, issues may arise in the signal acquisitionphase due to corruption of the signal from local electrical activity, inthe signal referencing phase due to poor referencing of the signal to anappropriate earth, and during the transfer of the signal to processingunits where the signal may be susceptible to interference. Thus, a needexists for devices, methods, and/or systems for reducing interferenceand stabilizing the signals being acquired and processed.

SUMMARY OF THE PRESENT INVENTION

Broadly defined, the present invention according to one aspect is anon-resistive contact sensor assembly, including: an electric fieldsensor device, including a dielectric component for receiving anelectrical signal from an object of interest and a signal processingcomponent for processing the electrical signal; a voltage regulator forcontrolling voltage to the dielectric component and the signalprocessing component; and a common ground reference for the dielectriccomponent and the signal processing component.

In a feature of this aspect, the dielectric component includes an activecomponent and a neutral component.

In another feature of this aspect, the signal processing componentincludes an A/D converter for converting the electrical signal receivedfrom the object of interest to a digitized signal.

In a further feature, the signal processing component includes an analogfilter for tuning the electrical signal received from the object ofinterest prior to the conversion of the electrical signal to a digitizedsignal by the A/D converter. In still further features, the dielectriccomponent, analog filter and A/D converter share a common groundreference; the analog filter and the A/D converter share a commonvoltage reference; the signal processing component includes a levelshift buffer between the analog filter and the A/D converter; and/or theanalog filter, the level shift buffer, and the A/D converter share acommon voltage reference.

In a further feature, the A/D converter is less than 50 mm away from thedielectric component. In a still further feature, the A/D converter isless than 20 mm away from the dielectric component. In a still furtherfeature, the A/D converter is less than 10 mm away from the dielectriccomponent. In a still further feature, the A/D converter is electricallyconnected to a dielectric component signal output by a signal connectionthat is less than 10 mm in length.

In a further feature, the A/D converter oversamples the electricalsignal at a rate of at least 16 times per sample to enhance signalclarity. In a still further feature, the A/D converter oversamples theelectrical signal at rate of at least 128 times per sample.

In another feature of this aspect, the circuitry has a ground plane toplayer, a ground plane bottom layer, and at least a partial ground planein all layers directly below the dielectric component.

In another feature of this aspect, the non-resistive contact sensorassembly further includes a casing in which the signal processingcomponent is surrounded or embedded and wherein the common groundreference is connected to the casing and to the dielectric component.

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in a circuit board.

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in anApplication-Specific Integrated Circuit (ASIC).

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in a combination of acircuit board with ASIC components.

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in a package thatphysically resembles a single component.

In another feature of this aspect, the neutral component includes adielectric membrane that interacts with the electric field to pick upthe electrical signal from the object of interest.

Broadly defined, the present invention according to another aspect is anon-resistive contact sensor assembly, including: an electric fieldsensor device, including a dielectric component for receiving anelectrical signal from an object of interest and an A/D converter forconverting the electrical signal received from the object of interest toa digitized signal; and circuitry interconnecting the dielectriccomponent and the A/D converter and including a layer, directly belowthe dielectric component, that is substantially entirely ground fill.

In a feature of this aspect, the dielectric component includes an activecomponent and a neutral component.

In another feature of this aspect, the non-resistive contact sensorassembly further includes an analog filter for tuning the electricalsignal received from the object of interest prior to the conversion ofthe electrical signal to a digitized signal by the A/D converter. Infurther features, the dielectric component, analog filter and A/Dconverter share a common ground reference; the analog filter and the A/Dconverter share a common voltage reference; the signal processingcomponent includes a level shift buffer between the analog filter andthe A/D converter; and/or the analog filter, the level shift buffer, andthe A/D converter share a common voltage reference.

In another feature of this aspect, the A/D converter is less than 50 mmaway from the dielectric component. In a further feature, the A/Dconverter is less than 20 mm away from the dielectric component. In astill further feature, the A/D converter is less than 10 mm away fromthe dielectric component. In a still further feature, the A/D converteris electrically connected to a dielectric component signal output by asignal connection that is less than 10 mm in length.

In another feature of this aspect, the A/D converter oversamples theelectrical signal at a rate of at least 16 times per sample to enhancesignal clarity. In a further feature, the A/D converter oversamples theelectrical signal at rate of at least 128 times per sample.

In another feature of this aspect, the circuitry has a ground plane toplayer, a ground plane bottom layer, and at least a partial ground planein all layers directly below the dielectric component.

In another feature of this aspect, the non-resistive contact sensorassembly further includes a casing in which the signal processingcomponent is surrounded or embedded and wherein a common groundreference is connected to the casing and to the dielectric component.

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in a circuit board.

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in anApplication-Specific Integrated Circuit (ASIC).

In another feature of this aspect, circuitry providing voltage andground reference for the components is implemented in a combination of acircuit board with ASIC components.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, embodiments, and advantages of the present inventionwill become apparent from the following detailed description withreference to the drawings, wherein:

FIG. 1A is a schematic diagram of a non-resistive contact sensorassembly in accordance with one or more preferred embodiments of thepresent invention;

FIG. 1B is a schematic diagram of the sensor head of FIG. 1A, shown inan inverted configuration;

FIG. 2 is a block diagram of portions of the sensor head of FIG. 1B,illustrating signal processing of the amplified signal from the sensordevice;

FIG. 3 is an enlarged top view of an exemplary implementation of thedielectric component and circuitry of FIG. 1B;

FIG. 4A is a physical circuit diagram of layer 1 of the printed circuitboard of FIG. 3;

FIG. 4B is a physical circuit diagram of layer 2 of the printed circuitboard of FIG. 3;

FIG. 4C is a physical circuit diagram of layer 3 of the printed circuitboard of FIG. 3; and

FIG. 4D is a physical circuit diagram of layer 4 of the printed circuitboard of FIG. 3.

DETAILED DESCRIPTION

As a preliminary matter, it will readily be understood by one havingordinary skill in the relevant art (“Ordinary Artisan”) that the presentinvention has broad utility and application. Furthermore, any embodimentdiscussed and identified as being “preferred” is considered to be partof a best mode contemplated for carrying out the present invention.Other embodiments also may be discussed for additional illustrativepurposes in providing a full and enabling disclosure of the presentinvention. As should be understood, any embodiment may incorporate onlyone or a plurality of the above-disclosed aspects of the invention andmay further incorporate only one or a plurality of the above-disclosedfeatures. Moreover, many embodiments, such as adaptations, variations,modifications, and equivalent arrangements, will be implicitly disclosedby the embodiments described herein and fall within the scope of thepresent invention.

Accordingly, while the present invention is described herein in detailin relation to one or more embodiments, it is to be understood that thisdisclosure is illustrative and exemplary of the present invention, andis made merely for the purposes of providing a full and enablingdisclosure of the present invention. The detailed disclosure herein ofone or more embodiments is not intended, nor is to be construed, tolimit the scope of patent protection afforded the present invention,which scope is to be defined by the claims and the equivalents thereof.It is not intended that the scope of patent protection afforded thepresent invention be defined by reading into any claim a limitationfound herein that does not explicitly appear in the claim itself.

Thus, for example, any sequence(s) and/or temporal order of steps ofvarious processes or methods that are described herein are illustrativeand not restrictive. Accordingly, it should be understood that, althoughsteps of various processes or methods may be shown and described asbeing in a sequence or temporal order, the steps of any such processesor methods are not limited to being carried out in any particularsequence or order, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and orders while still falling within the scope ofthe present invention. Accordingly, it is intended that the scope ofpatent protection afforded the present invention is to be defined by theappended claims rather than the description set forth herein.

Additionally, it is important to note that each term used herein refersto that which the Ordinary Artisan would understand such term to meanbased on the contextual use of such term herein. To the extent that themeaning of a term used herein—as understood by the Ordinary Artisanbased on the contextual use of such term—differs in any way from anyparticular dictionary definition of such term, it is intended that themeaning of the term as understood by the Ordinary Artisan shouldprevail.

Regarding applicability of 35 U.S.C. §112, ¶6, no claim element isintended to be read in accordance with this statutory provision unlessthe explicit phrase “means for” or “step for” is actually used in suchclaim element, whereupon this statutory provision is intended to applyin the interpretation of such claim element.

Furthermore, it is important to note that, as used herein, “a” and “an”each generally denotes “at least one,” but does not exclude a pluralityunless the contextual use dictates otherwise. Thus, reference to “apicnic basket having an apple” describes “a picnic basket having atleast one apple” as well as “a picnic basket having apples.” Incontrast, reference to “a picnic basket having a single apple” describes“a picnic basket having only one apple.”

When used herein to join a list of items, “or” denotes “at least one ofthe items,” but does not exclude a plurality of items of the list. Thus,reference to “a picnic basket having cheese or crackers” describes “apicnic basket having cheese without crackers,” “a picnic basket havingcrackers without cheese,” and “a picnic basket having both cheese andcrackers.” Finally, when used herein to join a list of items, “and”denotes “all of the items of the list.” Thus, reference to “a picnicbasket having cheese and crackers” describes “a picnic basket havingcheese, wherein the picnic basket further has crackers,” as well asdescribes “a picnic basket having crackers, wherein the picnic basketfurther has cheese.”

In various aspects, the present invention relates to methods ofattenuating or eliminating unwanted movement or electrostaticinterference on signals acquired via non-resistive contact sensors fromvarious entities, both biological and other. Such sensors may be used bythemselves, or may be used in combination with other sensors. The sensordata is utilized for detecting properties of the entities.

For biological entities, the invention utilizes an electric field sensoror sensors for the measurement of the structural and functionalcharacteristics of organs and other structures where the electric fieldsensor does not have resistive contact with the organism, conferringmultiple advantages. In various aspects, the present invention relatesto sensors, sensor housings, fastenings and sensor systems includingdevices and installations for assemblies for detecting structural andfunctional signatures associated with electric potentials that maydetect a displacement signature within the geomagnetic field, and/orspecific components and/or structures that are a component of thatentity or entities. There is preferably no resistive contact between theentity and the signal transduction component of the electric fieldsensor or sensors. Other sensor types may be added in to provide furtherinformation, such as for the identification and elimination orattenuation of unwanted electrostatic or movement signal associated withthe recording of non-resistive contact electric fields from that entity,in whatever state, such as during active or passive movement.

In particular, the present invention, in various aspects, relates tonovel methods and apparatuses for stabilizing the target signal whenusing an electric field sensor or sensors of the type that does not haveresistive contact with the entity, generally an organism, which is beingmonitored. In various aspects, the invention relates to combinations andpermutations of: an electric field sensor device, including a dielectriccomponent for receiving an electrical signal from an object of interest;a signal processing component, that may include an A/D converter forconverting the electrical signal received from the object of interest toa digitized signal; a voltage regulator for controlling voltage to thedielectric component and the signal processing component; a commonground reference for the dielectric component and the signal processingcomponent; and/or circuitry interconnecting the dielectric component andthe A/D converter and including a layer, directly below the dielectriccomponent, that is substantially entirely ground fill. Other featuresand aspects relate to combinations and permutations with any of theforegoing and applying an electric field to electrically stabilize thesensor zone; the use of a conductive casing to act as a reference forthe signal that is being acquired; the use of an analog to digitalconverter in the sensor head to digitally fix the signal; the use of abarrier (guard or shield) between the analog to digital converter tomitigate signal corruption the converter; a logic board to process thesignal in the sensor head; a compressive material or spring from anotherfixed structure, such as a helmet, to hold the referencing componentand/or the electrode firmly on the surface of the entity being measured;a cable or wireless transmitter to transmit the digitized signal; and/ora resistive contact electrode that may be incorporated into thereference casing or used as a separate component to add signalacquisition resilience.

Referring now to the drawings, in which like numerals represent likecomponents throughout the several views, one or more preferredembodiments of the present invention are next described. The followingdescription of one or more preferred embodiment(s) is merely exemplaryin nature and is in no way intended to limit the invention, itsapplication, or uses.

FIG. 1A is a schematic diagram of a non-resistive contact sensorassembly 10 in accordance with one or more preferred embodiments of thepresent invention. The sensor assembly 10 includes at least one sensorhead 12, a power supply 11, and a primary voltage regulator 13. In atleast some embodiments, the power supply 11 and voltage regulator 13 areexternal to the sensor head 12 but electrically connected by a power anddata cable 24. Each sensor head 12 includes at least one electric fieldsensor device 16. In at least some embodiment, the electric field sensordevice 16 is a dielectric component. The dielectric component 16 is atleast partially surrounded by, or embedded in, a housing 14, at leastportions of which may be made of anti-triboelectric material. Thehousing 14 may include a conductive casing (shielding) 15 that makesdirect resistive contact with the skin or other surface 20 on which thesensor assembly 10 is placed but is electrically isolated from thedielectric component 16. The casing 15 may be grounded by a groundconnection 26 to the power and data cable 24 to the unit 10. The casing15 may thus serve as a reference with regard to a target signal 30 fromthe object of interest.

In various respects, the sensor assembly 10 and sensor head 12, anddielectric component or other electric field sensor device 16 may haveone or more characteristics described in the '664 application ordescribed in the '918 application.

FIG. 1B is a schematic diagram of the sensor head 12 of FIG. 1A, shownin an inverted configuration. Each sensor head 12 further includes oneor more signal processing component 17,18,19, an optional secondaryvoltage regulator (not shown), circuitry 22 interconnecting the othercomponents as well as providing voltage and ground reference for theother components, and a power and data cable 24. The power and datacable 24 may include a ground connection 23, a signal connection 25, anda power connection 27. The circuitry 22, which may be implemented on aprinted circuit board or the like, interconnects the components,provides proper voltage levels from the voltage regulator or regulators,and provides a reference ground for the dielectric component 16 andvarious other components.

FIG. 2 is a block diagram of portions of the sensor head 12 of FIG. 1B,illustrating signal processing of the amplified signal from thedielectric component 16. After the signal from the electrode 16 isamplified, the resulting signal may be processed by the signalprocessing components 17,18,19. Such components may include an analogfilter 17 for tuning the signal of interest, a level shift and scalecircuit 19, including a buffer, that adjusts the resulting levels asdesired, or an A/D converter 18 for converting the output to a digitalsignal. As shown in FIG. 2, in at least some embodiments, a commonreference ground 23 is provided to each of the dielectric component 16,the analog filter 17, the level shift and scale circuit 19, and the A/Dconverter 18.

The A/D converter 18 preferably oversamples at a rate of at least 16times per sample, and still more preferably oversamples at a rate of atleast 128 times per sample, in order to enhance signal clarity. In atleast some embodiments, samples are taken 1000 times per second, so 16times oversampling (i.e., oversampling at a rate of 16 times per sample)would result in 16,000 total samples, and 128 times oversampling (i.e.,oversampling at a rate of 128 times per sample) would result in 128,000total samples. In at least some of these embodiment, the oversampling iscontrolled such that data transfer operations and other operations arenot occurring at the same time, thereby reducing or minimizing noisearound the dielectric component 16. Furthermore, in at least someembodiments, the A/D converter 18 is located less than 50 mm away fromthe dielectric component 16 at least for a purpose of reducing orminimizing risk of unwanted parasitic capacitance. In at least some ofthese embodiments, the A/D converter 18 is located less than 20 mm, andpreferably less than 10 mm, away from the dielectric component 16. Inparticular, the electrical connections for the signals between thesignal outputs of the dielectric component 16 and the signal inputs ofthe A/D converter 18 are preferably less than 10 mm in length. Finally,in at least some embodiments, more than one sensor head 12, more thanone dielectric component 16 in each sensor head 12, or both, areutilized, and their outputs are coordinated. In at least some of theseembodiments, the dielectric components 16 are synchronized so that theyare both sampling at the same time and transferring data at the sametime.

In at least some embodiments, the electric field sensor device 16 of thesensor head 12 is a dielectric component 16 is made up of an activecomponent 42 and a neutral component 44. The active component 42 mayinclude an ultrahigh impedance amplifier, high and low pass filters, andwell controlled input bias with active guarding and shielding allaround. The neutral 44 component may include a dielectric membrane thatinteracts with the electric field to pick up the signal, which is thenamplified. This dielectric component 16 generally (and the dielectricmembrane particularly) may or may not be exposed to the exterior of thehousing 14, but is preferably capacitively coupled to the skin or othersurface 20 of the entity being analyzed. In at least some embodiments,the dielectric component 16 is arranged to have direct physical contactwith the skin or other surface 20 on which the sensor assembly 10 isplaced.

In at least some embodiments, some or all of the signal processing iscarried out within the confines of the sensor casing 15, and in at leastsome embodiments, the amplification is likewise carried out within theconfines of the sensor casing 15. In at least some embodiments, thesignal processing components 17,18,19 is also shielded from theelectrode 16 itself by the circuitry 22, which may serve as an internalpartition providing an electrical field barrier against the electrode 16and the amplification thereof. In this regard, it will be appreciatedthat in at least some embodiments, amplification likewise takes place onthe opposite side of the circuitry 22 from the A/D converter 18 andother signal processing components. Advantageously, the shieldingoffered by the partition 22 helps to prevent the A/D converter 18 andother components from being affected by interference caused by variouselectrical effects.

FIG. 3 is an enlarged top view of an exemplary implementation of thedielectric component 16 and circuitry 22 of FIG. 1B. In this exemplaryimplementation, the dielectric component 16 is carried on a four-layerprinted circuit board 22. It will be appreciated however, that thesemiconductor device 22 may be implemented in a variety of physicalforms, including a standalone circuit board, as an application-specificintegrated circuit or “ASIC,” or the like.

FIG. 4A is a physical circuit diagram of layer 1 51 of the printedcircuit board 22 of FIG. 3; FIG. 4B is a physical circuit diagram oflayer 2 52 of the semiconductor device 22 of FIG. 3; FIG. 4C is aphysical circuit diagram of layer 3 53 of the printed circuit board 22of FIG. 3; and FIG. 4D is a physical circuit diagram of layer 4 54 ofthe semiconductor device 22 of FIG. 3. In some ways, layers 1 and 4 maybe considered as signal layers or planes (i.e., layers used primarilyfor routing signal wires), while layer 2 may be considered as a groundplane (i.e., a layer used primarily for routing ground wires) and layer3 may be considered as a power plane (i.e., a layer used primarily forrouting power wires). The four large squares in the left half of eachlayer are the mounting pads for the dielectric component 16. Smallcircles represent vias connecting one layer to another, with blackcircles generally showing ground connections from the ground plane toother planes and white circles generally showing other connectionsbetween planes. Squares, rectangles, and other shapes generallyrepresent devices, pads, and the like, and are mostly located on layer1. Wires connecting vias, devices, pads, and the like together aregenerally represented by black lines, with the thickest black linesgenerally represent voltage controlled power supply connections beingdistributed from the power plane.

Perhaps most notably, the grey, cross-hatched areas represent groundfill 32. Nearly all of layer 2 (the ground plane) is occupied by suchfill 32, which may for example be a continuous layer of metal, with theonly exceptions being vias passing through layer 2 for power and signalconnections between layer 1 and layers 3 and 4. However, the otherlayers all include large expanses of such fill 32 as well. For example,ground fill 32 occupies all of layer 3, with the only exceptions beingvias passing therethrough, for power and signal connections betweenlayer 3 and layers 1 and 4, and power wires being routed in layer 3 fordistribution to layers 1 and 4. Similarly, ground fill 32 occupies allof layer 4, with the only exceptions being vias passing therethrough forpower and signal connections between layer 4 and layers 1 and 3, andsignal wires being routed in layer 4 for distribution to layer 1. Eventhe main signal plane, layer 1, has large areas of ground fill 32between various devices, pads, signal wiring, power wiring, and thelike, including substantially all of the area beneath the dielectriccomponent 16 (i.e., the area between the four large mounting pads). Allof these areas of ground fill 32 are tied together at numerous locationsby vias (represented by the small black circles), thereby ensuring aconsistent and uniform ground connection for all active components. Itwill be appreciated that because of the large areas of ground fill 32 inthe signal and power planes, and particularly in layers 3 and 4, theseplanes can in some contexts be described as “ground planes” themselves.

Various advantages may be achieved using one or more of the foregoingembodiments of the present invention. The robustness of the measurementof the electrical signature of an entity or sub-component of that entitymay be increased. A signal being measured or analyzed may be protectedcloser to the source, thereby protecting it from corruption. Thestability of the signal may be enhanced. The signal-to-noise ratio foran electric field sensor may be enhanced. The effect of electrostaticcharge interference with an electric field sensor may be minimizes oreliminated entirely. The use of electric field sensors during exerciseand daily activities may be increased, as can the usability of electricfield sensors with different types of clothing and when clothing ismoving due to exercise or external forces (like wind). Similarly, theusability of electric field sensors may be increased when there isexternal contact that would otherwise knock the sensor loose or thatwould result in charge transfer to the entity being measured oranalyzed. Conversely, the likelihoods of contact electrification, sensorDC drift, and sensor saturation may all be decreased.

Based on the foregoing information, it will be readily understood bythose persons skilled in the art that the present invention issusceptible of broad utility and application. Many embodiments andadaptations of the present invention other than those specificallydescribed herein, as well as many variations, modifications, andequivalent arrangements, will be apparent from or reasonably suggestedby the present invention and the foregoing descriptions thereof, withoutdeparting from the substance or scope of the present invention.

Accordingly, while the present invention has been described herein indetail in relation to one or more preferred embodiments, it is to beunderstood that this disclosure is only illustrative and exemplary ofthe present invention and is made merely for the purpose of providing afull and enabling disclosure of the invention. The foregoing disclosureis not intended to be construed to limit the present invention orotherwise exclude any such other embodiments, adaptations, variations,modifications or equivalent arrangements; the present invention beinglimited only by the claims appended hereto and the equivalents thereof.

What is claimed is:
 1. A non-resistive contact sensor assembly,comprising: an electric field sensor device, including a dielectriccomponent for receiving an electrical signal from an object of interestand an A/D converter for converting the electrical signal received fromthe object of interest to a digitized signal; circuitry interconnectingthe dielectric component and the A/D converter and including a layer,directly below the dielectric component, that is substantially groundfill, the circuitry shielding the A/D converter from the dielectriccomponent and serving as an internal partition providing an electricalfield barrier against the dielectric component; and a fastening forfastening the non-resistive contact sensor assembly to an organism formeasurement of characteristics of an organ of the organism.
 2. Thenon-resistive contact sensor assembly of claim 1, wherein the dielectriccomponent includes an active component and a neutral component.
 3. Thenon-resistive contact sensor assembly of claim 2, further comprising ananalog filter for tuning the electrical signal received from the objectof interest prior to the conversion of the electrical signal to adigitized signal by the A/D converter.
 4. The non-resistive contactsensor assembly of claim 3, wherein the dielectric component, analogfilter and A/D converter share a common ground reference.
 5. Thenon-resistive contact sensor assembly of claim 3, wherein the analogfilter and the A/D converter share a common voltage reference.
 6. Thenon-resistive contact sensor assembly of claim 3, wherein the signalprocessing component includes a level shift buffer between the analogfilter and the A/D converter.
 7. The non-resistive contact sensorassembly of claim 6, wherein the analog filter, the level shift buffer,and the A/D converter share a common voltage reference.
 8. Thenon-resistive contact sensor assembly of claim 2, wherein the A/Dconverter is less than 50 mm away from the dielectric component.
 9. Thenon-resistive contact sensor assembly of claim 8, wherein the A/Dconverter is less than 20 mm away from the dielectric component.
 10. Thenon-resistive contact sensor assembly of claim 9, wherein the A/Dconverter is less than 10 mm away from the dielectric component.
 11. Thenon-resistive contact sensor assembly of claim 10, wherein the A/Dconverter is electrically connected to a dielectric component signaloutput by a signal connection that is less than 10 mm in length.
 12. Thenon-resistive contact sensor assembly of claim 2, wherein the A/Dconverter oversamples the electrical signal at a rate of at least 16times per sample to enhance signal clarity.
 13. The non-resistivecontact sensor assembly of claim 12, wherein the A/D converteroversamples the electrical signal at rate of at least 128 times persample.
 14. The non-resistive contact sensor assembly of claim 2,wherein the circuitry has a ground plane top layer, a ground planebottom layer, and at least a partial ground plane in all layers directlybelow the dielectric component.
 15. The non-resistive contact sensorassembly of claim 2, further comprising a casing in which the signalprocessing component is surrounded or embedded and wherein a commonground reference is connected to the casing and to the dielectriccomponent.
 16. The non-resistive contact sensor assembly of claim 2,wherein circuitry providing voltage and ground reference for thecomponents is implemented in a circuit board.
 17. The non-resistivecontact sensor assembly of claim 2, wherein circuitry providing voltageand ground reference for the components is implemented in anApplication-Specific Integrated Circuit (ASIC).
 18. The non-resistivecontact sensor assembly of claim 2, wherein circuitry providing voltageand ground reference for the components is implemented in a combinationof a circuit board with ASIC components.
 19. A non-resistive contactsensor assembly, comprising: an electric field sensor device, includinga dielectric component for receiving an electrical signal from an objectof interest and an A/D converter for converting the electrical signalreceived from the object of interest to a digitized signal; circuitryinterconnecting the dielectric component and the A/D converter andincluding a layer, directly below the dielectric component, that issubstantially entirely ground fill, the circuitry shielding the A/Dconverter from the dielectric component and serving as an internalpartition providing an electrical field barrier against the dielectriccomponent and amplification thereat; and a fastening for fastening thenon-resistive contact sensor assembly to an organism for measurement ofcharacteristics of an organ of the organism.
 20. A non-resistive contactsensor assembly, comprising: an electric field sensor device, includinga dielectric component for receiving an electrical signal from an objectof interest and an A/D converter for converting the electrical signalreceived from the object of interest to a digitized signal, thedielectric component comprising an amplifier; circuitry interconnectingthe dielectric component and the A/D converter and including a layer,directly below the dielectric component, that is substantially entirelyground fill, the circuitry shielding the A/D converter from thedielectric component and serving as an internal partition providing anelectrical field barrier against the dielectric component andamplification thereat; and a fastening for fastening the non-resistivecontact sensor assembly to an organism for measurement ofcharacteristics of an organ of the organism.